The present invention relates to a semiconductor device, and more specifically, to integration of an air spacer with a self-aligned contact in a transistor.
In the continuing effort to decrease the size of transistors, gate pitch is decreasing along with gate size. That is, the distance between the gate and a contact above a source or drain region is smaller. This has led to the formation of a self-aligned contact (SAC). By recessing the gate metal and forming an etch stop or SAC cap above the gate, an etch of the trench that defines the contact can be allowed to self-align without a danger that the contact will connect to the gate metal. In certain devices, not every source and drain region requires a contact. For example, in a not-and (NAND) circuit, n-type field effect transistors (NFETs) are electrically connected in series by shared source and drain regions. In this type of device, forming a contact on internally connected sources and drains is not necessary. The same is true for a not-or (NOR) circuit.